JPH02114488A - Induction heating cooker - Google Patents

Abstract

PURPOSE:To make it feasible to operate plural heating coils through the simple structure of the cooker in the title, by connecting two heating coils in series or in parallel to each other via a switch, and then doing the on-off control of electricity being supplied to the one-side heating coil through the make-and- break operation of a switch. CONSTITUTION:A first heating coil 2, a second heating coil 3 and a switching element 4 are connected in series to one another for being connected to both ends of a DC power supply 1, while there are also both a series resonance capacitor 5 and a switch 6 by breaking and making of which electricity being supplied to the second coil 3 is turned on and off. Besides, a control unit 7 controls the on-off operation of a switching element 4. This makes it feasible to do simultaneous heating by the first heating coil 2 and the second heating coil 3 through the on-off operation of the switch 6 or it feasible to do heating only by the first heating coil 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an induction cooking device having a plurality of heating coils.

Conventional technology Induction heating cookers that apply high-frequency current to a heating coil and inductively heat a load that is magnetically coupled to the heating coil are safe, clean, and safe.
The advantages of high efficiency are understood and it is becoming popular in ordinary households. In the past, induction heating cookers were mainly used for cooking in pots or boiling water, but due to the cleanliness of induction heating cookers, in recent years they have been used for grilling like hot plates. It's starting. However, when cooking grilled foods, it is necessary to have a location with strong heat to bake the food all at once, and a location with weak heat to keep the cooked food warm. It was difficult with the configuration of

In order to solve this problem, it has conventionally been common to have two heating coils, each of which is provided with a switching element and a resonant capacitor.

FIG. 4 shows a conventional circuit. In FIG. 4, 1 is a DC power supply, 11 is a first heating coil, 12 is a second heating coil, 13 is a first switching element, 14 is a second switching element, 15 is a first resonant capacitor, 16 is a second resonant capacitor, and 17 is a control unit that controls on/off of the first and second switching elements 13 and 14. With this configuration, a high frequency current is applied to the first and second heating coils 11.12 by turning on and off the first and second switching elements 13.14, thereby inductively heating the load magnetically coupled to each of them. Ta.

Problems to be Solved by the Invention However, according to the configuration of the conventional example, two switching elements are required, and a control section 17 for controlling the on/off of these two switching elements 13 and 14 is also required. Furthermore, if two switching elements 13 and 14 are operated at the same time, interference noise will be generated due to the difference in the operating frequencies of the two elements, so in order to prevent this, the control unit 17 alternately operates and stops one of the switching elements. The problem was that the configuration was complicated, as control was performed to stop the other when the other was in use.

In view of the above problems, an object of the present invention is to operate a plurality of heating coils with a simple configuration.

Means for Solving the Problems In order to achieve the above object, the present invention includes a DC power supply, a series circuit of a first heating coil, a second heating coil, and a switching element connected to the DC power supply, and at least the above-mentioned A series resonant capacitor connected in parallel to either the switching element or the first heating coil, a switch connected in parallel to the second heating coil, and a control unit that controls on/off of the switching element. have,
By opening and closing the switch, the second heating coil is turned on and off.

Further, the first heating coil is connected in parallel to a series circuit of a second heating coil and a switch, and a switching element is connected to this parallel circuit, and a resonant capacitor is connected to the first heating coil or the switching element. They are connected in parallel.

Function According to the above configuration, two heating coils are connected in series or in parallel via a switch, so two heating coils can be used to realize two types of burners with high and low heating power, such as on a hot plate. Control can be performed by turning on and off one switching element, and heating of one heating coil can be stopped by turning off a switch.

Moreover, since the operating frequencies of the first and second heating coils are the same, no interference noise is generated.

Example A first embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, 1 is a DC power supply, 2 is a first heating coil, 3 is a second heating coil, 4 is a switching element, and the first heating coil 2, the second heating coil 3, and the switching element 4 are They are connected in series and connected to both ends of the DC power supply 1. 6 is a series resonant capacitor, and 6 is a switch. By opening and closing this switch 6, power supply to the second heating coil 3 is turned on and off. 7 is a control unit that controls on/off of the switching element 4;

According to the above configuration, by turning on and off the switch 6, it is possible to perform heating by the first heating coil 2 and the second heating coil 3 at the same time, or to perform heating by only the first heating coil 2.

In this embodiment, the switching element 4 is shown as a bipolar transistor and an anti-parallel diode, but it is clear that other elements may be used.

Next, a second embodiment of the present invention will be described with reference to FIG.

In FIG. 2, 1 is a DC power supply, 2 is a first heating coil, 3 is a second heating coil, 4 is a switching element, and the first heating coil 2, the second heating coil 3, and the switching element 4 are They are connected in series and connected to both ends of the DC power supply 1. 5 is a series resonant capacitor, 8 is a parallel resonant capacitor, and 6 is a switch. By opening and closing this switch 6, power supply to the second heating coil 3 is turned on and off.

7 is a control unit that controls on/off of the switching element 4;

In the above configuration, a parallel resonant capacitor 8 is added compared to the first embodiment. Therefore, it is still possible to control two heating coils 2.3 at the same time with one switching element 4,
It has the characteristics that the regenerative current to the DC power supply 1 is small, and the fluctuation in frequency depending on whether or not power is supplied to the second heating coil 3 is small.

Next, a third embodiment of the present invention will be described with reference to FIG.

In FIG. 3, 1 is a DC power supply, 2 is a first heating coil, and 4 is a switching element, and a series circuit of the first heating coil 2 and the switching element 4 is connected to the DC power supply 1. 3 is a second heating coil, and 6 is a switch which forms a series circuit with the second heating coil 3 and is connected in parallel to the first heating coil 2. 9 is a resonant capacitor, which is connected in parallel to the first heating coil 2 here. 7 is a control unit that controls on/off of the switching element 4; With this configuration, power supply to the second heating coil 3 is controlled by closing the switch 6 all together.

Even in this case, the high frequency current is supplied to the first heating coil 2 and the second heating coil 3 through the switching element 4.
Controlled by turning on and off. In this embodiment, the resonant capacitor 9 is connected in parallel with the first heating coil 2, but the same effect can be achieved even if the resonant capacitor 9 is connected in parallel with the switching element 4.

Effects of the Invention As is clear from the above embodiments, according to the present invention, in an induction heating cooker that requires two types of burners, high and low, such as a hot plate, i.e., two heating coils, two heating coils can be used. Since it is possible to supply power to two heating coils by controlling one switching element, it is possible to provide a simple circuit configuration and at low cost.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of an induction heating cooker showing a first embodiment of the present invention, Fig. 2 is a circuit diagram of an induction heating cooker showing a second embodiment of the invention, and Fig. 3 is a circuit diagram of an induction heating cooker showing a second embodiment of the invention. FIG. 4 is a circuit diagram of a conventional induction cooking device. 1°°°・°DC power supply, 2°°゛・first heating coil, 3゛°=i2 heating coil, 4... switching element, 6°°°゛° series resonant capacitor, 6°°°
°" switch, 7...Control unit, 8...Parallel resonant capacitor, 9...Resonant capacitor. Name of agent: Patent attorney Shigetaka Awano and one other person Figure

Claims (2)

[Claims] (1) A DC power supply, a series circuit of a first heating coil, a second heating coil, and a switching element connected to the DC power supply, and parallel to at least one of the switching element or the first heating coil. a resonant capacitor connected to the second heating coil, a switch connected in parallel to the second heating coil, and a control section that controls on/off of the switching element, and by opening and closing the switch, the second heating coil is heated. An induction heating cooker characterized by turning on and off electricity to the coil. (2) a DC power supply, a series circuit of a first heating coil and a switching element connected to the DC power supply, and a series circuit of a second heating coil and a switch connected in parallel to the first heating coil; , a resonant capacitor connected in parallel to the first heating coil or the switching element;
An induction heating cooker comprising: a control unit that controls on/off of the switching element, and energization to the second heating coil is turned on and off by opening and closing the switch.